nixos/release.nix: remove warning about missing state version for images

  pkgs = import ./.. { system = "x86_64-linux"; };

  versionModule =

    { system.nixos.versionSuffix = versionSuffix;

  versionModule = { config, ... }: {

    system.nixos.versionSuffix = versionSuffix;

    system.nixos.revision = nixpkgs.rev or nixpkgs.shortRev;

    # At creation time we do not have state yet, so just default to latest.

    system.stateVersion = config.system.nixos.version;

  };

  makeModules = module: rest: [ configuration versionModule module rest ];